In the developmental process, reproductive cells carry out spermatogenesis via a differentiation process that includes meiosis. This differentiation process is different from that of somatic cells and consists of three main steps. The first step is the proliferation of spermatogenous cells and differentiation into primary spermatocytes. The second is the meiosis of primary spermatocytes, and the third is the transformation into sperms.
Owing to the progress in Molecular Biology, recent years have seen the isolation of several genes specifically expressed in these stages. For example, Hox-1.4 (Propst, F. et al. (1988) Oncogene 2:227-33), ferT (Sarge, K. D. et al. (1994) Biol Reprod 50:1334-1343) of the HSP70 family, and TESK1 (Toshima, J. et al. (1995) J. Biol. Chem. 270:31331-31337) that is a serine-threonine kinase, have been reported as genes specific to primary spermatocytes. However, still very little is known about the biological and physical roles of their gene products.
Genes expressing specifically in the differentiation process of reproductive cells carry a fundamental and vital role that decides the fate of those cells, and thus, defects in these genes are considered to be a cause of diseases such as infertility. Therefore, genes expressing specifically in the differentiation process of reproductive cells are recently gaining wide attention as targets in the development of pharmaceutical drugs. Such drugs can be used for the prevention and treatment of diseases such as infertility caused by defects in reproductive cell differentiation.